Researchers suggest coal ash and tailings dam disasters could be prevented

coal
Credit: CC0 Public Domain

A trio of researchers from the King Abdullah University of Science and Technology, the University of the Witwatersrand and Geosyntec has published a Perspectives piece in the journal Science. Carlos Santamarina, Luis Torres-Cruz and Robert Bachus note in the article that many lives are lost each year when coal ash or tailings dams fail, causing mudslides. Many such failures are preventable.

Iron mining produces a known as tailings. Tailings are typically dumped into man-made ponds, which are more often than not dammed up to prevent them from oozing downhill when it rains. Similar ponds are constructed to contain waste produced by coal power plants. Besides representing a pollution problem, the ponds are also mudslide hazards. The researchers point out that thousands of people around the world have been killed by such mudslides over the past century. They suggest it is time that governments engage more fully with those building and maintaining such ponds.

The researchers note that mudslides from tailings or ash occur when the dam holding the material gives way. Many people believe that the reason such dams give way is because of the contents and what happens to them. Evidence of liquefaction of pond materials is almost always in evidence along mudslide routes. But prior study has shown that liquefaction almost always happens after the dam gives way, not before. Instead, the researchers suggest that the major reason for most of the disasters is failure to follow best engineering practices in building and maintaining the dams.

One of the biggest problems, the researchers point out, is that proper action is not taken during heavy rain causing overflow, which puts excess stress on the dam. Another problem is layering on the bottom of such ponds that result in deposits with different hydromechanical properties—this usually leads to weaknesses in the system. Also, cementation can loosen sediment structures, which can also weaken the system. And problems can also develop when material is compressed near the dam. They note also that preexisting weaknesses in the foundation of the dam can lead to failure later, and so can piping erosion or mineral buildup.

The researchers conclude by suggesting more attention to such ponds, because the mudslides that can result when they fail appear to be far more preventable than many in the field have suggested.


Explore further

How bacteria can prevent coal ash spills

More information: J. Carlos Santamarina et al. Why coal ash and tailings dam disasters occur, Science (2019). DOI: 10.1126/science.aax1927
Journal information: Science

© 2019 Science X Network

Citation: Researchers suggest coal ash and tailings dam disasters could be prevented (2019, May 10) retrieved 17 July 2019 from https://phys.org/news/2019-05-coal-ash-tailings-disasters.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
50 shares

Feedback to editors

User comments

May 10, 2019
Why in the world don't they mix the coal ash with a binder, leaving it solid form?

Putting it in solid block form would eliminate the overwhelming majority of problems asociated with coal ash, and be much more economical.

May 11, 2019
Why in the world don't they mix the coal ash with a binder, leaving it solid form?

Putting it in solid block form would eliminate the overwhelming majority of problems asociated with coal ash, and be much more economical.


Same reason they don't convert nuclear waste to vitrified glass, the way they planned it in the 1980's; money.

May 12, 2019
Yes, unfortunately money is always their their biggest driving force but with this the expense would be less than making and retaining holding ponds - not to mention the cost of cleanup after a 'spill'.

The biggest problem with the nuclear waste is that it is still radioactive even if you have it in the vitrified glass form. That makes it more expensive and problematic to handle even after you have shaped into a form that can be more easily physically manipulated.

The coal ash by comparison, would be largely inert once it was bound up in a solid form.

May 14, 2019
Why not put the junk in glass Thorium boy??? What do you think physicists are stupid? Of course, we would do that if it was f****** even feasible. The goddamn glass will f****** melt fool or It might just be easier engineering wise to do it otherways.

May 15, 2019
And so another intelligent adult discussion gets stopped because a foul mouthed moron with nothing to add except kindergarden level insults.

What a shame that the Idiocracy is already here.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more